The results of the study of oscillograms of voltage,current,pulsed electric power and energy input into the plasma of an overstressed nanosecond discharge between aluminum electrodes in argon and mixtures of nitrogen ...The results of the study of oscillograms of voltage,current,pulsed electric power and energy input into the plasma of an overstressed nanosecond discharge between aluminum electrodes in argon and mixtures of nitrogen with oxygen(100-1)at pressures in the range of 13.3-103.3 kPa are presented,the emission plasma spectra are studied.It is shown that in mixtures of nitrogen with oxygen at atmospheric pressure,nanoparticles of aluminum oxide(Al2O3)are formed,the luminescence of which manifests itself in the spectral range of 200-600 nm and which is associated with the formation of F-,F+-centers and more complex aggregate formations based on oxygen vacancies.Calculations of the electron-kinetic coefficients of plasma,transport characteristics,such as mean electron energies in the range 5.116-13.41 eV,are given.The electron concentration was 1.6∙10^(20)m^(-3)-1.1∙10^(20)m^(-3)at a current density of 5.1∙10^(6)A/m^(2)and l.02∙10^(7)A/m^(2)on the surface of the electrode of the radiation source(0.196·10^(-4)m^(2)).Also drift velocities,temperatures and concentrations of electrons,specific losses of the discharge power for elastic and inelastic processes of collisions of electrons per unit of the total concentration of the mixture from the reduced electric field strength(E/N)for a mixture of aluminum,nitrogen,oxygen,rate constants of collisions of electrons with aluminum atoms on the E/N parameter in plasma on a mixture of aluminum vapor,oxygen and nitrogen=30:1000:100000 Pa at a total mixture pressure of P=101030 Pa are given.展开更多
Using the Splitting Hopkinson Pressure Bar （SHPB） experimental system, investigations were made into the dynamic mechanical performances of underground soft rocks. The experiments proved that the measured stress-str...Using the Splitting Hopkinson Pressure Bar （SHPB） experimental system, investigations were made into the dynamic mechanical performances of underground soft rocks. The experiments proved that the measured stress-strain curves display the characteristics of plastic deformation. By making use of a revised overstress constitutive formula for the stress model and by taking into account that the strain rate and strain are a function of I - E（t）/Eo, a revised overstress constitutive formula for the stress model was simplified by applying dimensional analysis and consequently, a simplified overstress formula was obtained for the stress model. Then, by taking into consideration the effects of damage under a dynamic load on the dynamic loading strength of the rock, the continuous damage theory and the statistical strength theory were introduced into the development of the simplified overstress constitutive formula for the stress model. Hence, a damage-based constitutive formula for an overstress model, which can be appropriately applied to the analysis of full dynamic stress-strain curves, was developed. By using the simplified damage-based constitutive formula for an overstress model, the actually measured curves are fitted, indicating that the fitting curves and those actually measured are in good agreement.展开更多
文摘The results of the study of oscillograms of voltage,current,pulsed electric power and energy input into the plasma of an overstressed nanosecond discharge between aluminum electrodes in argon and mixtures of nitrogen with oxygen(100-1)at pressures in the range of 13.3-103.3 kPa are presented,the emission plasma spectra are studied.It is shown that in mixtures of nitrogen with oxygen at atmospheric pressure,nanoparticles of aluminum oxide(Al2O3)are formed,the luminescence of which manifests itself in the spectral range of 200-600 nm and which is associated with the formation of F-,F+-centers and more complex aggregate formations based on oxygen vacancies.Calculations of the electron-kinetic coefficients of plasma,transport characteristics,such as mean electron energies in the range 5.116-13.41 eV,are given.The electron concentration was 1.6∙10^(20)m^(-3)-1.1∙10^(20)m^(-3)at a current density of 5.1∙10^(6)A/m^(2)and l.02∙10^(7)A/m^(2)on the surface of the electrode of the radiation source(0.196·10^(-4)m^(2)).Also drift velocities,temperatures and concentrations of electrons,specific losses of the discharge power for elastic and inelastic processes of collisions of electrons per unit of the total concentration of the mixture from the reduced electric field strength(E/N)for a mixture of aluminum,nitrogen,oxygen,rate constants of collisions of electrons with aluminum atoms on the E/N parameter in plasma on a mixture of aluminum vapor,oxygen and nitrogen=30:1000:100000 Pa at a total mixture pressure of P=101030 Pa are given.
基金supported by funds from the National Natural Science Foundation of China (Nos. 51374013, 51174005 and 51134012)the Huo Yingdong Funds for Young Teachers to Conduct Researches on Basic Sciences (No. 121050)+1 种基金the academic research activities subsidies for academic and technical leaders and backup candidate in Anhui provincethe funds for the Doctoral Program of Higher Education (No. 20133415110006)
文摘Using the Splitting Hopkinson Pressure Bar （SHPB） experimental system, investigations were made into the dynamic mechanical performances of underground soft rocks. The experiments proved that the measured stress-strain curves display the characteristics of plastic deformation. By making use of a revised overstress constitutive formula for the stress model and by taking into account that the strain rate and strain are a function of I - E（t）/Eo, a revised overstress constitutive formula for the stress model was simplified by applying dimensional analysis and consequently, a simplified overstress formula was obtained for the stress model. Then, by taking into consideration the effects of damage under a dynamic load on the dynamic loading strength of the rock, the continuous damage theory and the statistical strength theory were introduced into the development of the simplified overstress constitutive formula for the stress model. Hence, a damage-based constitutive formula for an overstress model, which can be appropriately applied to the analysis of full dynamic stress-strain curves, was developed. By using the simplified damage-based constitutive formula for an overstress model, the actually measured curves are fitted, indicating that the fitting curves and those actually measured are in good agreement.
